Generally, a strut-type suspension used for front wheels of a four-wheeled vehicle has structure wherein a strut assembly and a coil spring are combined, the strut assembly comprises an external cylinder that is integral with a main shaft, and a hydraulic shock absorber that is accommodated in the external cylinder. As such strut-type suspensions, there is a type in which a piston rod of the strut assembly rotates when the strut assembly rotates together with the coil spring in steering operation, and a type in which a piston rod does not rotate. In both types, sometimes a thrust slide bearing of synthetic resin, instead of a rolling bearing, is used between an installation mechanism for installing a strut assembly in a vehicle body and an upper spring washer member for a coil spring, so that the strut assembly rotates smoothly.
The installation mechanism for installing the strut assembly in the vehicle body uses an installation plate for supporting one end of the piston rod of the hydraulic shock absorber. However, in this type of installation mechanism, complex structure of the installation mechanism in addition to the need for the installation plate for supporting one end of the piston rod causes high cost.
To cope with the problems, Patent Literature 1 proposes a thrust slide bearing in an installation mechanism for installing a strut assembly in a vehicle body, wherein the thrust slide bearing, instead of an installation plate, supports one end of a piston rod, to simplify the structure of the installation mechanism and to reduce cost. Further Patent Literature 1 proposes a combination mechanism of the thrust slide bearing and a piston rod.
The thrust slide bearing described in Patent Literature 1 comprises: a ring-shaped first bearing body of synthetic resin, which has a ring-shaped upper surface and a ring-shaped engaging outer periphery; a ring-shaped second bearing body of synthetic resin, which is superimposed over the first bearing body so as to be relatively rotatable about the axis of the first bearing body, and has a ring-shaped lower surface being opposed to the ring-shaped upper surface of the first bearing body; a thrust slide bearing means, which is positioned between the ring-shaped upper surface of the first bearing body and the ring-shaped lower surface of the second bearing body and has at least one of a lower surface in slidable contact with the ring-shaped upper surface of the first bearing body, and an upper surface in slidable contact with the ring-shaped lower surface of the second bearing body; a ring-shaped top cover, which has a ring-shaped engaging inner periphery surface that engages with the ring-shaped engaging outer periphery surface of the first bearing body; and a ring-shaped metal plate, which is positioned between a ring-shaped upper surface of the second bearing body and a lower surface of the ring-shaped top cover such that a lower surface of the metal plate is in contact with the ring-shaped upper surface of the second bearing body and an upper surface of the metal plate is in contact with the lower surface of the ring-shaped top cover. In this thrust slide bearing, the ring-shaped metal plate has a ring-shaped inner periphery surface of a smaller diameter than the inner diameters of the ring-shaped inner periphery surfaces of both bearing bodies and the ring-shaped top cover, and this structure solves the above problems effectively.